Dynamoelectric machine



Aug. 20, 1963 A. w. BRUNOT 3,101,423

DYNAMOELECTRIC MACHINE Filed Dec. 12, 1958 Inventor: Albert W. Brunotmotors.

' s e ttrmfi e seer. t9 some ited States 3,101,423 DYNAMOELECTRICMACHINE I Albert W. Brunet, Swampscott, Mass assignor to GeneralElectric Company, a corporation of New York Filed Dec- 12, 1958, Ser.No. 779,978 1 Claim. (Cl. 310-86) the stator windings from theenvironment in which the,

motor operates. This design ofmotor has found particular utility ininstallations where a high pressure pump,

driven by the motor, circulates relatively high temperature liquid in aclosed external loop. In orderto properly cool the operating parts ofthe'motor, a second and separate g system circulates coolant through thegap or clearance provided between the cylindrical cans respectivelymounted on the rotor and stator cores. Since it'has been found desirableto have the liquid in the gap between the cans at the same pressure asthat existing in the closed loop, pressure from the pump is reflectedinto the gap by appropriately spaced small openings near the shaft.This, 'however, presents problem-s =of-support for'the stator can andother parts subject to deformation as a' result of the extremely highpressures. This invention concerns itself witha highlpressure seal usedfor preventing ingress of sw m Patented Aug. 20, 1,963

deform the parts. These stresses in some canned motors may be so greatas to require scrapping of the various parts in the area where the ringis welded in position. A further disadvantage is that the cost involvedin replacing the pants with the accompanying liability of having toreplace portions thereof because of misfits, make present practicesprohibitive from a cost standpoint. V

In still other constructions where heavy welds are not resorted to, thehydraulic pressures in and adjacent the air gap, cause the parts tobuckle or otherwise deform thus causing leakage into that portion of thestator enclosing the coil conductors.

The object of my invention-therefore, is to eliminate the disadvantagescited above by providing a ring of the desired strength and. flexibilityfor sealing the bottom end of the stator while simultaneouslyproviding aconstruction capable of facilitating removal and replacement of theringwith-a minimum of time, effort, and expense."

-In carrying out my invention, I close the bottom .end of a verticallydisposedstator. with a ring of trapezoidal cross section. The upperouter surface of the ring is shaped to receive the coil end turns whichare located-in a i dead air space when the ring is fitted in positionbetween the stator can andframe. The central portion or body of the ringcomprises a section of heavy material extending the complete distancebetween the stator can and the frame enclosing the stator to provide thestructural supliquidinto that area housing the windings by closing the llower end ofthe stator, while simultaneously supporting thebottorn endof the can fixed in the-bore of the stator."

Many different designs have been resorted to-for supplying the necessarystructural support to the'stator parts,

including thei can disposed in -the stator borgwhilesiinul- Itarieouslyj; performinga sealing function; '[In 3 the: usual Yconstructionjthe stator pu'ncliings s'uppo'rtthe can through out amajonportion of its' length and a pair of abutting cylindr'ical rings'of'sufiicient strength to withstand presport necessary forresistingforces created by the high pressure'fluid circulated in the gap'orspacebetween the cans. The ring has an upwardly and axially directedtubular member adapted for close fit With the stator can and itsuppermost end terminates in an end plate used for containing the statorlaminations'. The lower portion. of

the ring has another tubular member extending downwardly from theoutermost. part of the heavy'section where the diameter is :the'same asthe inside of the stator frame." In order to provide an eifective seal,the inner a: and outer surfaces of the tubular members respectively,

sures in the-neighborhoodbf 3,000 p.s;i. serve as'backing I membersfor'the remaining portions bf'the can,' 'jl while als'o-serying'ttoseal thebottoinherid of the. stator when are-welded .to. the caninthe'statorborejand to the frame enclosing the stator. The ringtherefore is capable of withstanding the forces of liquid in the gapandrotor bearing cavity whichjtend to deform, the ring and pull, i-taway itis in a vertical position," The-bottom or-lower ring -is I equipped with"a"cavity for housing the endwturns positioned betweeninwardly'dire'cted fingers provided in parts associated Witli thejstator.-To obtain a tight seal, the bottomrin'gisjwel'ded 'at its innerperipheral ends=to the a can wtiile tlie' outer peripheral edge islikewise-weldedfto the-inner surface of;lthestatoriframe. Theweld on theconstruction is' that the cylindrical ring must bet rem'oyed A tomakeithecoilsaccessible for repairt The likelihoodof 7 coil burnoutafforexample, or other damage toth'e insulatie s-re uiring coil, replacement,is notremote because of the high temperatures to whichthesmachine issubjected;'v Removal oftheycylindrical ring must theieforeibemad 1? isara 'stw ai "bymachini utthe weld j jacent parts in this area are inftherarige of thousandths principal diifiof an inch, son'iedistortionojccu'i'sl: The Why :libi Messr d g. ments? t 2 outjthe several views,there is shownin FIGURE I, ,a

fro'rn the inner surface of thestator frame wh'ile simultaneouslypreventing-leakage into the ,-area enclcsing the coil end turns.- 1'. 1t

)While the specificationconcludes withia claim: 5 larly pointing out anddistinctly,claiming the subjectmat ter which I regard as my invention,it is;believed the=in vention will; be oetter understood from thefollowing description taken in connection .yvith'the accompanyingdrawingin whichz.

-. FIGURE 1 is a partia lview eff'an sign a was in! eluding arote-randstator and showing the disposition of the closure ringgandww i w jv ,amodification'ofthe ring shownin FIGURE 2 is FIGUREI. 7 H I I a Referringnow to the drawing ,wherein like [reference characters designate. likeor corresponding par-ts throughsquirrel cage rotor 1t) supported on ashaft i2 arranged for positioning within-a stator 14, ,The statorcomprises a pluralityg-of laminations having conductor slots thereinforgreceivingfcoils havingend turns in. Stainless steel reattached toperipheral surface of l ructio ps1. pressure s circ'ulatedf the' bore ofthe. stator to form the air. l t 's l inns t the-stator c v 1 anyappreciable stress in-the :thin areau;

theieyent the'rin'g sectiondoes' d'eflect in'an axialupward Vdirection-at the'bore, {the corner ofthe ringattached to 5- 5 thethin'tubular-sectio'ntends toglift away from the stator ii Atlthe same time,the'backing of the thin tube "isremoved atthis'pointso that there' is -anet'increase in U forceitendingi to reduc e the .deflectioniat the-bore.Prob} l'lmS'Of s tress thereforeare not present in the thin tubu- "casintive seal for preventing leakage of liquid into the area containing theend turns, a closure ring is positioned adjacent the bottom end of themotor as shown'in FlG- URE -1. '"The. ring 2t}, which preferablycomprises a singular casting of material, is in. the shape of a heavytrapezoidal member having a small diameter inner tubular member22Ijoined with a larger diameter tubularmernoer 24 by a thick section26. As illustrated, the thin tubular member 24 is welded to thestatorcasing or frame 28 at St). The tubular) member 2260f smaller diameter,is fitted in abutting relationship with the can 18 and is welded theretoat 31. V-

As previously mentioned, liquid under pressure of ap-. proXimatelyLOOOp.'s.i. is circulated through the air gap thus exerting hydraulic forceson the ring in the direction indicated by the arrows; The heavy ringsection 26 is supported by a shoulder 32 in the stator casing and underthe action of the hydraulic'pressureion the innerradius keepdefoirnation to a satewminimum. The selection of a ring of. trapezoidal crosssection effectively provides the-necessary support audit ismorerigid'than a rectangular sectionfof the same weight. Thesmallerdiameter tubular member 22 of the ring is supported in aradialdirection by fingers 34 of a stator lamination clamping disc '36 bu'tisfree to move axially without loading the stator pu'nchings. Theconstruction which makes possible such radial and axial movementforabsorbing the forces created by hydraulicpressure, is more fullydisclosed-in the patent application of J; A. Walsh and H. C. Ward,Serial N0.- 7 7 9,703,filed' December."- 11, 1958, entitled Stator CanSupport, assigned'to the same assignee as the present invention andfiled concurrently herewith.

This construction comprising the thick central section 26 .and thetubular rnemberi 22' has suflicient cross section thickness towithstandthe hydraulic forces tending'tocause outwarddefiormationof member 2 2.The bending 'movement' which otherwise would oocur' about point 325 is rtherefore minimized to thepoint where. its effect is negligible. v e i 1If Withl the forcesa'ctingfon ring 20 in the direction indicated bythearrows, :and rotation tends to occur about or point 32, 'a stressis,exerted'o'n the'seal'weld tjoining V ,7 the tubular'mernber ,24 to' thestator casing, It willbe noted that the lengthof member is several timesits thickness.-- SinceQthis section of thering issupported byasing,.thehydraulic pressure does not produce la'r member and sincethebending: stresses are l'owyit is not subjected to large hoop; actionbecause of ,thebackingv provided byfthe stator frameor casing 28. As aresult, "loads of apprec' ble magnitude-are not imposedupon fi sss' wd-i 1 t Tlie i h fthe ring? as 1 closure; member and can supp'ort isthat j minimum deflection is"providedw ith" minimum weight advantagesresulting from the "combined useot Ithius permitting the use io'f a'very small sea weld; The]v permits the application However," in a yvideonly a few mils clearance. As illustrated, thecan 13 is arranged toextend outwardly a greater distance than in the previous embodiment andis designed to bear against a tubular member 40 positioned in engagementwith the stator clamping disc 36 at 42. The other end of member 49 has ashoulder 44 engaging-a step providedvin a heavy cylindrical ring 46. Theouter periph 46, thus positioning it accurately inthe machine Thefunction served by the retaining ring is to eliminate a p and lowersurface, tends to rotate about the point32.3 Since' this movement causesthe inner radius to move axially upwardly, it is desirable to minimizethe rotative 7 effect by -suitably. choosing the proportions of the ring'to eral portio Ofring 46 is likewise fitted into a stepped portion -48of the stator casing 28. When the parts are assembled in this manner, aretaining ring so, is fitted into place in the'stator casing and isarrangedto have a portion of its surface engage the flat portion 52of'ri'ng tendency of the cylindrical ring 46 from pulling away frompoint 32 as the Weld material contractsupon cooling.

An outer tubular memberQSd of thin cross section is v I mounted withinthe casing 23 and is welded at f o-and 5S to provide a seal etleotiveinpreventing; ingressof water J into the areawherethe'end turns arelocated.

The, construct-ions described above suggest that the teachingsareapplicable to other equipment involving a pair of vessels that mustprovide aise'al against high fluid pressures. The invention has beendisclosed in con nectionwith dynamoelectricimachines,'bu-t it will beevident that any apparatus carrying high internalpressures andrequiringboth a seal-for preventing leakage into ondesirable areas and'structu-ral support for protecting the parts against deformation, mayutilize the teachings here in. Many modifications and variations arepossible in light of the above disclosure. i it therefore is to beunderstood that within the scope of the appended claim, the inventionmay be practiced otherwise than as specifically described; I I j I WhatI- claim as new 'andgidesire, to secureby Letters Patent of the UnitedStates is; f 1 A motor comprising astat-or core enclosedin .aframe aandarotorp-ositioned inthe bore of the stator, coils-hav- H jfior'zhold-ing the.latter:in apredetermined-p 5.5

' saidzfirsttubular inembe providing a"oonst uctionflcapableof-witdraulic forces imposed on; the ,innerfcylindrical l surfaces or thecanon-the stator inner surface while' simultane P ou-slypreventing-leakage; otwaterrinto the stator p orlt n housing the coilsing, enditurns protruding. outwar-dly from. the {SWIG/1', -a:cyl-i-ndrical' can ;on the statorqand rotor surfaces forming an'faingaptherebetween, a clamping ring attached oeach v end of the stator forsupportingthei-laminations, a first I tubular member having its infiersu-r-facepfixed iniiuid-jj tight relationship: with the stator canLandincluding one end in 'firrn engagement with said clamping ring, ,acylirr-v Q ting "with the "other end 1 of said tubule-remember andpositioned betweensaid mem ber and the frame and thereby-definingacavity enclosing ldricaliming havinga shoulder o the end turnsflinaldejad air space, a groove termed inthe inner surface'o-f said statorframe iorrreceivingtthe router ;su r. face of thecylindrical'ring,laretaining member fitted in'the internal'wa-ll of thestat r firarnea 6 arranged for t time nd acontact :with the exposedpontion oflsaid yhpdrical second. tubular "member having; a diameter; greai ted i n the jfile of this patent 1 3 UNITED STATES PATENTS isle 1 vingitsfper'ip heral surface i ngage'mentjwiththestator frame-and a dthereor in t ling "said

